Stereological study of Leydig cell density in the guinea pig testis

Stereological analysis of Leydig cell and macrophage volume density along the long axis of the guinea pig testis was assessed quantitatively by histometric point counting. Morphological identification of Leydig cells was accomplished by staining for 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD), whereas macrophages were identified by vital staining (trypan blue). The average percentage of Leydig cell density constitutes about 10.17 +/- 0.23% at the cranial level (level 1) and about 8.8 +/- 0.21% at the caudal level (level 4). Leydig cell density through four testicular levels showed no significant difference among levels 1, 2, and 3, whereas level 4 was significantly different. The percentage of macrophage density, on the other hand, was approximately 0.4% +/- SEM per cross-sectional profile. It may thus be concluded that the macrophage density within the guinea pig testis does not bias histometric studies of the Leydig cell population to any significant degree, but that regional differences in Leydig cell volume density could influence validity of sampling if tissue procurement is from different testicular levels in successive experiments.